Methods and systems for operating a vehicle driveline

Abstract

Systems and methods for improving operation of a hybrid vehicle are presented. In one example, an engine is accelerated to a speed of a driveline integrated starter/generator before the engine is coupled to the driveline integrated starter/generator.

Description

RELATED APPLICATIONS[0001]The present application claims priority to U.S. of America Provisional Patent Application 61 / 643,160 filed on May 4, 2012, the entire contents of which are hereby incorporated by reference for all purposes.FIELD[0002]The present description relates to a system and methods for improving drivability and fuel economy of a vehicle. The methods may be particularly useful for engines that are selectively coupled to an electrical machine and a transmission.BACKGROUND AND SUMMARY[0003]A hybrid vehicle may be provided with a driveline disconnect clutch. The driveline disconnect clutch may be closed to couple an engine with an electric machine. The driveline disconnect clutch may be opened to decouple the engine from the electric machine. The engine may provide torque to the driveline when the driveline disconnect clutch is closed. The engine is stopped when the driveline disconnect clutch is open to conserve fuel. However, starting the engine and coupling the engine...

AI Technical Summary

Benefits of technology

[0005]By operating an engine at an idle speed uncoupled from a driveline and accelerating the engine to a speed of the driveline, it may be possible to reduce driveline torque disturbances when driver demand torque increases. In particular, driveline torque disturbances may be reduced during an increase in driver demand torque by closing a driveline disconnect clutch that couples the engine to the driveline when engine speed and driveline speed are equivalent. Thus, the driveline integrated starter / generator may provide the driver demand torque for a short period of time, and then, engine torque can supplement driveline integrated starter / generator torque after the engine is coupled to the driveline. In this way, driveline torque response may be improved while the possibility of a driveline torque disturbance is reduced.

[0006]The present description may provide several advantages. Specifically, the approach may improve driveline torque response. Further, the approach may reduce the possibility of driveline torque disturbances.

Problems solved by technology

However, starting the engine and coupling the engine to the driveline may result in one or more driveline torque disturbances which may be objectionable to a driver.

Further, the approach may reduce the possibility of driveline torque disturbances.

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